1. Field of the Invention
The present invention generally relates to a rotary drilling head utilized in combination with a rotary drilling apparatus, such as a conventional drilling apparatus employing a Kelly bar connected to a drill string with drilling fluid, either air or liquid, being used in the drilling operation with the drilling head providing a seal and wiper or stripper for the Kelly bar during its vertical and rotational movement with solid particles entrained in the drilling fluid being discharged through an outlet port in the base of the rotary drilling head with the relative rotational components being supported by thrust bearing assemblies and sealed by seal assemblies and continuously lubricated by a pressurized lubricating mist.
2. Description of Relevant Art
My prior U.S. Pat. No. 3,285,352, issued Nov. 15, 1966, discloses a rotary drilling head which includes the basic components of a base, housing or outer body and a spindle or inner body journaled and sealed in relation thereto and the structure and operation of the device disclosed in that patent is incorporated herein by reference thereto. Also, the prior art cited during prosecution of the application which matured into U.S. Pat. No. 3,285,352 also discloses rotary drilling heads which operate in a similar manner. A continuing problem with known rotary drilling heads is the wear encountered due to the abrasiveness of solid particles of the formation, or the like, entrained in the drilling fluid whether it be air, gas, liquid, or any combinations thereof. Wear caused by relative rotation between components in an abrasive environment results in the necessity of replacing components which requires that the drilling apparatus be shutdown while the drilling head is undergoing repair or replacement of parts.